Bleaching agents are generally classified into reducing and oxidizing bleaching agents, among which the oxidizing bleaching agents are widely used because of their bleaching effect. The oxidizing bleaching agents are further classified into chlorine and oxygen types. Undesirably, the chlorine type bleaching agents cause discoloration of articles treated therewith so that they cannot be applied to colored clothes, and they have a disagreeable odor. The oxygen type bleaching agents are superior to the chlorine type bleaching agents in that they can be applied in a wider range of articles and they are free of an irritating smell and are easy to use.
Among the oxygen type bleaching agents, however, hydrogen peroxide and peroxides capable of releasing hydrogen peroxide in aqueous solution, for example, percarbonates, perborates, and hydrogen peroxide adducts of pyrophosphates, citrates, sodium sulfate, urea, and sodium silicate exhibit a lower bleaching action than the chlorine type bleaching agents. Further, the oxygen type bleaching agents cannot provide a sufficient bleaching effect within a short period of bleaching treatment and thus require a substantially extended period of time to achieve a sufficient bleaching effect, particularly at low temperatures.
It has also been a common practice to combine peroxides with bleaching activators, for example, certain O or N-acyl compounds such as tetraacetylethylenediamine (TAED), tetraacetylglycol uryl (TAGU), and pentaacetyl glucose (PAG) to obtain enhanced bleaching effect. These conventional bleaching activators, however, do not have a satisfactory activating effect and may even aid the bleaching agents to cause discoloration of articles treated therewith. For these and other reasons, the oxygen type bleaching agents have not gained a satisfactory beaching effect which is comparable to the chlorine type bleaching agents.